Acoustic convection apparatus

ABSTRACT

A convective cooling apparatus cools an electronic device including at least one heat-generating component and enclosed in a case having cooling medium such as air or fluid therein. The convective cooling apparatus neither attempts to increase the velocity of flow in the cooling medium nor replaces the cooling medium with other material as prior art cooling apparatus did. Instead, it utilizes the instability which is inherent in the flow of the cooling medium. In the convective cooling apparatus, by using a driver for generating a signal tuned to the characteristic frequency of the flow, a an acoustic vibrator is driven to provide acoustic waves. The acoustic waves induce resonance of flow, which renders the cooling medium vigorously mixed, which, in turn, enhances the heat dissipation from the device.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an acoustic convection apparatus foruse in a system where uniform distribution of heat and density is neededand to a convective cooling at apparatus for cooling heat-generatingcomponents in electronic or electrical devices.

2. Description of the Related Art

As electronic devices become more complex and highly integrated, mucheffort has been made to improve the performance of apparatus for coolingsuch devices. To enhance the ability to dissipate heat from anelectronic devices, such as computers or communication equipments, whichcontain many heat-generating components, heat should be forciblytransferred from the components to the surrounding cooling medium. Asthe electronic devices become more compact, passages of the coolingmedium become narrower, thereby slowing the flow of the cooling medium.Moreover, in narrow passages, there exists only laminar flow withouteddies. With the laminar flow, the cooling fluid is not actively mixed,which in turn prevents efficient convective heat transfer from thecomponents to the cooling medium.

There have been several attempts to solve this problem. One of them isso called forced convection, which is to increase the velocity of thecooling medium by using a cooling fan or a pump. As the heat generationfrom the electronic components increases, the air flow rate should beincreased by using a high powered fan or a pump. However, such a coolingsystem induces high power consumption and noise. Moreover, a fan or apump cannot be easily used in very small devices.

Another approach is to shift the movement of the fluid from laminar toturbulent flow by adding turbulence-inducing material. However, thesemethods may suffer from noise and low reliance. The fan used for thecooling application is also being employed to enhance fluid mixing inthermal systems such as an oven, a furnace, a drying machine or arefrigerator. Air flow generated from the fan makes the distribution oftemperature or density uniform to a certain degree. However, such asystem also shows low efficiency because the air flow may not beuniform.

SUMMARY OF THE INVENTION

An object of the present invention is therefore to provide a convectionapparatus which reduces the nonuniformity of air flow in a space whereuniform distribution of temperature and density is needed, therebyimproving the efficiency of an overall system disposed in the space.

Another object of the present invention is to provide a convectivecooling apparatus for effective heat dissipation from electronicdevices, which are compact and lightweighted.

In accordance with an aspect of the present invention, there is provideda convection apparatus for providing convective flow of medium in asystem, which comprises a driver for generating a driving signal with apredetermined frequency and a vibrator, in response to the drivingsignal, for generating acoustic waves to an interior of said system.

In accordance with another aspect of the present invention, there isprovided a convective cooling apparatus for cooling an electronic deviceincluding at least one heat-generating component and enclosed in a casehaving cooling medium therein. The convective cooling apparatus of thepresent invention neither attempts to increase the velocity of flow inthe cooling fluid nor replaces the cooling medium with other material asprior art cooling apparatus did. Instead, it utilizes the hydraulicinstability which is inherent in the flow of the cooling medium. In theconvective cooling apparatus of the present invention, by using a driverfor generating a signal tuned to a characteristic frequency of flow, anacoustic vibrator is driven to provide acoustic waves. The acousticwaves induce resonance in flow, which renders the cooling fluidvigorously mixed, which, in turn, enhances the heat dissipation from thedevice.

BRIEF DESCRIPTION OF THE DRAWINGS

The aforementioned aspect and other features of the invention areexplained in the following description, taken in conjunction with theaccompanying drawings wherein:

FIG. 1 shows a front view and a block diagram of an acoustic convectionapparatus of the present invention;

FIG. 2 shows a front and a side views of a convection oven where theacoustic convection apparatus of the present invention is installed;

FIG. 3 shows temperature transition of the upper and lower parts of theconvection oven shown in FIG. 2;

FIG. 4 shows a block diagram of a convective cooling device inaccordance the present invention;

FIG. 5 shows a block diagram of a convective cooling device of thepresent invention for use in an electric appliances whose characteristicfrequency of flow does not vary much;

FIG. 6 shows temperature change of a heat-generating component whenacoustic waves of 20 Hz is applied thereto;

FIG. 7 shows temperature change of a heat-generating component whenacoustic waves of 50 Hz is applied thereto;

FIG. 8 shows temperature change of a heat-generating component whenacoustic waves of 100 Hz is applied thereto;

FIG. 9 shows the relationship between the frequency of the acousticwaves and rate of temperature change resulting from the application ofthe acoustic waves;

FIG. 10 shows the relationship between the amplitude of the drivingsignal and rate of temperature change resulting from the application ofthe acoustic waves; and

FIG. 11 shows a map of the rate of temperature change obtained byvarying the amplitude of a driving signal and the frequency of acousticwaves.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a front view and a block diagram of an acoustic convectionapparatus of the present invention. The acoustic convection apparatuscomprises a vibrator 4 and a driver 3 including a signal generator 1 andan amplifier 2. Preferably, the signal generator 1 and the amplifier 2are designed as one integrated electronic circuit. The vibrator 4 can beimplemented using an acoustic speaker which can easily generate acousticpressure signals. Alternatively, a membrane or a piston which vibratesperiodically by a motor may be used.

The signal generator 1 provides a time-periodic electrical signal suchas a sinusoidal, sawtooth or rectangular wave. The generated signal isvoltage and current amplified in the amplifier 2. The amplified signalis sent to the vibrator 4 as a driving signal which drives the vibrator4 to generate time-periodic acoustic waves. When a user turns on aswitch (not shown) of the convection apparatus, the driving signal isprovided from the driver 3 to the vibrator 4. In response, the vibrator4 provides acoustic waves which cause an acoustic convection by whichone can obtain uniform distribution of heat and density in a space wherethe convection apparatus is located.

In the signal generator 1, the frequency of the time-periodic signal maybe determined in a couple of ways which will be described in detail withreference to FIGS. 4 and 5. Briefly, the frequency may be fixed beforeoperating the convection apparatus or may be modified in real-timeduring operation.

FIG. 2 shows front and side views of a convection oven where an acousticconvection apparatus of the present invention is installed. A convectionoven is built by installing a convection apparatus in an ordinary gas orelectric oven. The convection apparatus improves the efficiency of theoven by circulating air therein.

An acoustic vibrator 5 is located on the inner wall near the center ofthe oven so that it can provide acoustic waves to the interior of theoven 9. A driver 7 is built on a control board at the upper part of theoven. When a convection switch 6 is turned on, the driver 7 provides adriving signal to the acoustic vibrator S. The acoustic vibrator 5 thenprovides acoustic waves to the interior of the oven 9, thereby makingthe heat distribution in the oven uniform.

FIG. 3 shows the result of an experiment for testing the convectionapparatus of the present invention. Specifically, it is a graphrepresenting temperature transitions of upper and lower parts of aconvection oven provided with the convection apparatus of the presentinvention. Before the convection apparatus was turned on, thetemperature difference between the upper and the lower parts of the ovenwas about 25° C. After the convection apparatus was turned on after 5minutes, the temperature difference is reduced to less than 1° C. in aminute. On turning off the convection apparatus after 20 minutes, thetemperatures returned to the initial values so that the air in the ovenassumed stratified temperature distribution.

By inducing uniform distribution of heat and density, the convectionapparatus of the present invention increases the efficiency and thusreduces the energy consumption of a system where it is used. Theconvection apparatus may be applied to a refrigerator, a freezer, adrying machine or a welding furnace to improve the efficiency thereof.It may also be used to improve the air distribution of anair-conditioned space.

The convection apparatus described above can be used for coolingelectronic devices. The convection apparatus provides cooling effects byincreasing the convective flow of cooling medium over heat-generatingcomponents in such devices. FIG. 4 shows one embodiment of such coolingapparatus. Specifically, FIG. 4 shows a convective cooling apparatus 10for an electronic device where the frequency of the driving signal isdetermined according to a characteristic frequency of the electronicdevice.

In FIG. 4, the electronic device is enclosed in a case 17 and includes aheat-generating component 18 such as a CPU of a computer. An opening 19is built in a side wall of the case 17 to allow air flow from theinterior of the case to the outside.

The cooling apparatus 10 includes a signal detector 11 for receiving aflow signal from the cooling medium in the case 17, a driver 20 forgenerating a driving signal, an acoustic vibrator 16 for providingacoustic waves to the interior of the case 17 in response to the drivingsignal. In household electronic devices, the cooling medium wouldtypically be air.

The signal detector 11 is disposed near the heat-generating component 18to receive a flow signal, i.e., a signal induced by the flow of thecooling medium in the case 17. The signal detector 11 may comprise atleast one of a velocity, a temperature, a pressure and a densitysensors.

The flow signal detected at the signal detector 11 is sent to the driver20 which includes a frequency analyzer 12 for analyzing the flow signalto determine a characteristic frequency of flow, a frequencysynchronizer 13 for providing a frequency signal which represents thecharacteristic frequency determined in the frequency analyzer 12, asignal generator 14 for generating the driving signal in response to thefrequency signal, and an amplifier 15 for amplifying the driving signal.

Specifically, the flow signal is first sent to the frequency analyzer 12which analyzes the frequency components of the flow signal by using thefast fourier transform and detect a characteristic frequency of flow,i.e., a dominant frequency among the analyzed frequency components ofthe flow signal.

The characteristic frequency detected in the frequency analyzer 12 isprovided to the frequency synchronizer 13 which provides the frequencysignal, i.e., a signal representing the characteristic frequency, to thesignal generator 14. The frequency signal may have any format as long asit conforms with an input of the signal generator 14.

The signal generator 14 generates the driving signal in response to thefrequency signal. The driving signal may be any signal having thecharacteristic frequency, such as a sine wave, a sawtooth wave, or arectangular wave, although a sine wave is preferred to minimize noisesgenerated from the apparatus 10. The driving signal is amplified at theamplifier 15 and then fed to the acoustic vibrator 16.

The acoustic vibrator 16 generates acoustic waves having thecharacteristic frequency of flow in response to the amplified drivingsignal. The acoustic vibrator 16 may be implemented by using an acousticspeaker capable of easily generating acoustic waves. Alternatively, apiston, a cam, a membrane or a flap associated with a motor may performthe same function. The acoustic waves cause a resonance in the flowwithin the case 17, which activates heat transfer from theheat-generating component 11 to the ambient atmosphere through the heatdissipating opening 19. The acoustic vibrator 16 may be located in anywall of the case as long as the acoustic waves are directed to theinterior of the case 17. Alternatively, a small acoustic vibrator may beplaced near the heat-generating component 18.

FIG. 5 shows another embodiment of a cooling apparatus employing theinventive convection apparatus for use in an electronic device where thecharacteristic frequency of flow does not vary much in time. The coolingapparatus 30 shown in FIG. 5 includes a signal generator 21, anamplifier 22 and an acoustic vibrator 23. In case the amount of heatgenerated at an electronic device does not vary much in time, thecharacteristic frequency of flow does not change much, either. In thiscase, the characteristic frequency may be set to a predetermined valuewithout dynamically changing it in real-time. In the cooling apparatus30, the signal generator 21 is preset to generate a driving signalhaving the predetermined frequency. Therefore, the cooling device 30does not include such elements as a signal detector, a frequencyanalyzer and a frequency synchronizer which are employed in the coolingapparatus 10 to determine the characteristic frequency and inform it tothe signal generator 14. The driving signal is fed to the amplifier 22and then to the acoustic vibrator 23, which provides acoustic waves tothe interior of a case 24 of the electronic device. Then, like thecooling apparatus 10 shown in FIG. 4, a resonance occurs in the case 24and heat dissipation from a heat-generating component 25 to the ambientatmosphere through a heat dissipating opening 26 is improved.

In the cooling apparatus 10 or 30, the characteristic frequency of flowis less than several hundred Hz which is much lower than the mechanicalresonant frequency of the electronic appliances. Thus, the applicationof the acoustic waves does not have an adverse effect on the structuralstability of the devices. Moreover, compared with prior art coolingapparatus employing a fan to promote the movement of the cooling medium,the apparatus of the present invention produces less noise and can bebuilt more compactly.

To find out the performance of the cooling apparatus of the presentinvention, experiments were conducted using an electronic device havinga heat-generating component and including the cooling apparatus of thepresent invention. FIG. 6 to FIG. 11 show the temperature change of theheat-generating component when acoustic waves of various frequencies andamplitudes are applied to the heat-generating component by the coolingapparatus.

First, FIGS. 6, 7 and 8 depict the effect of application of acousticwaves whose vibrating frequencies are 20 Hz, 50 Hz and 100 Hz,respectively. FIG. 6 shows that the temperature of the component isinitially 88° C. and is reduced by 10 on degrees after applying theacoustic waves for 10 minutes. FIG. 7 also shows that the temperature isreduced below 70° C. after 10 minutes of acoustic wave application.After the acoustic wave application was suspended, the temperature ofthe component went back up to the initial value. FIG. 8 shows that 100Hz wave has little effect on the cooling of the component. FIGS. 6 to 8indicate that there is an optimal frequency for cooling aheat-generating component by inducing a resonance of flow.

FIG. 9 shows the relationship between the frequency of the acousticwaves and rate of temperature change. It shows that the maximumreduction of temperature of the heat-generating component is 12 percentwhen the frequency of the acoustic waves is around 50 Hz.

To find out the effect of the amplitude of the driving signal on thetemperature change, the cooling apparatus was operated with a fixedfrequency of 50 Hz while varying the amplitude of the signal fed to theacoustic vibrator. Rate of temperature change is depicted in FIG. 10which indicates that the maximum reduction of temperature is around 16Volt.

The effects of the frequency and amplitude of a driving signal on thetemperature change is summarized in FIG. 11 which shows the distributionof the rate of temperature change when varying the frequency andamplitude of a driving signal. The frequency and amplitude for obtainingmaximum temperature change depend upon characteristics of eachelectronic devices such as size or shape, etc.

The cooling apparatus of the present invention can be easilyincorporated into portable computers and communication devices havingvery small space inside. The cooling apparatus can be easily optimizedto provide maximum cooling effects by adjusting a vibrating frequency.While a number of fans are needed to effectively cool a device havingmany heat-generating components, one cooling apparatus of the presentinvention is sufficient to cool such a device. In sum, the apparatus ofthe present invention provides improved cooling performance whileallowing the devices to become smaller, lighter and less noisy.

The cooling apparatus of the present invention can also be used in apower converter and an atomic reactor where cooling performance has acritical impact on the operation and safety of the overall system. Itcan also be employed in a heat exchanger for chemical processes, arefrigerating and air-conditioning system, and a radiator system forheating and cooling a building.

The present invention has been described with reference to a particularembodiment in connection with a particular application. Those havingordinary skill in the art and access to the teachings of the presentinvention will recognize additional modifications and applicationswithin the scope of the present invention. It is therefore intended bythe appended claims to cover any and all such applications,modifications, and embodiments within the scope of the presentinvention.

1. An apparatus for promoting the cooling of an electronic deviceenclosing at least one heat-generating component, comprising: a signaldetector for receiving a flow signal of a cooling medium inside theelectronic device; a driver, in response to the flow signal from thesignal detector, for providing a driving signal whose frequency issynchronized with a characteristic frequency of the flow of the coolingmedium, wherein said characteristic frequency is a dominant frequencyamong analyzed frequency components of a flow signal of theheat-absorbing medium; and a vibrator, in response to the drivingsignal, for generating an acoustic wave to an interior of the electronicdevice, wherein the driver includes: a frequency analyzer for detectingthe characteristic frequency of the flow of the cooling medium based onthe flow signal; a frequency synchronizer for providing a frequencysignal which represents the detected characteristic frequency; a signalgenerator, in response to the frequency signal from the frequencysynchronizer, for providing the driving signal; and an amplifier foramplifying the driving signal to a predefined level.
 2. The apparatus ofclaim 1, wherein the signal detector includes at least one of velocity,temperature, pressure, and density sensing means with respect to thecooling medium.
 3. An apparatus to promote the cooling of a convectiondevice enclosing at least one heat-generating component and aheat-absorbing medium, comprising: a signal detector to receive a flowsignal of the heat-absorbing medium; a driver, in response to the flowsignal from the signal detector, to provide a driving signal having apredetermined frequency synchronized in accordance with a characteristicfrequency of a flow of the heat-absorbing medium, and including anamplifier to amplify the driving signal to a predefined level; and avibrator to generate and apply an acoustic wave to the heat-absorbingmedium contained in an interior of the convection device in response tothe amplified driving signal, wherein the convection device comprises aheat dissipating opening formed therein to dissipate heat generated bythe at least one heat-generating component to ambient atmosphereaccording to the acoustic wave generated by the vibrator and the drivingsignal of the driver.
 4. The apparatus of claim 3, wherein thepredetermined frequency is determined in accordance with at least one ofa size and a shape of the convection device.
 5. A temperature controlapparatus to control temperature within a convection device having acase and a heat-absorbing medium within the case, the temperaturecontrol apparatus comprising: a signal detector that detects a flowsignal of the heat-absorbing medium; a driver to generate a drivingsignal with a predetermined frequency in response to the flow signaldetected, the predetermined frequency being determined in accordancewith a characteristic frequency of the flow signal of the heat-absorbingmedium, and including an amplifier to amplify the driving signal whennecessary; a heat dissipating opening provided through a wall of thecase; and an acoustic vibrator that generates acoustic waves and appliesthe acoustic waves to the heat-absorbing medium using the generateddriving signal of the driver to activate heat transfer from theheat-absorbing medium to ambient atmosphere through the heat dissipatingopening.
 6. The temperature control apparatus of claim 5, wherein thesignal detector detects at least one of velocity, temperature, pressureand density of air.
 7. The temperature control apparatus of claim 5,wherein the driver comprises: a frequency analyzer that analyzes theflow signal detected and determines a characteristic frequency of theflow signal detected by the signal detector; a frequency synchronizerthat provides a frequency signal representing a characteristic frequencydetermined in the frequency analyzer; a signal generator that generatesthe drive signal in response to the frequency signal; and the amplifierthat amplifies the drive signal to a predetermined level.
 8. Aconvection apparatus to enhance a convective flow of a heat-absorbingmedium in a housing thereof, the convection apparatus comprising: aheat-generating component disposed in the housing; a signal detectorthat detects a flow signal within the heat-absorbing medium; a heatdissipating opening provided through a portion of a wall of the housingto dissipate heat therein; and a driver to generate a driving signalhaving a frequency signal synchronized with a characteristic frequencyof the flow signal of the heat-absorbing medium based on the flowsignal, to generate a driving signal in response to the generatedfrequency signal, the driving signal being synchronized with thecharacteristic frequency detected, and including an amplifier to amplifythe driving signal and to drive an acoustic member using the amplifieddriving signal; and an acoustic vibrator to provide acoustic waves tothe heat-absorbing medium within the housing in response to the drivesignal to the driver to induce a uniform distribution of heat generatedby the heat-generating component to the heat-absorbing medium, theacoustic waves activating heat transfer from the heat-absorbing mediumto ambient atmosphere through the heat dissipating opening.
 9. Theconvection apparatus of claim 8, wherein the signal detector detects atleast one of velocity, temperature, pressure and density of air.
 10. Theconvection apparatus of claim 9, wherein the driver comprises: afrequency analyzer that analyzes the detected characteristic of theheat-absorbing medium and determines a characteristic frequency of theheat-absorbing medium; a frequency synchronizer that provides afrequency signal representing the characteristic frequency determined bythe frequency analyzer; and a signal generator that generates the drivesignal in response to the frequency signal from the frequencysynchronizer; and the amplifier that amplifies the drive signal to apredetermined level.
 11. An acoustic convection apparatus having aheat-generating component to heat a heat-absorbing medium within ahousing of the acoustic convection apparatus, the acoustic convectionapparatus comprising: a heat dissipating opening in a wall of thehousing; a signal detector that detects a flow signal of theheat-absorbing medium; a driver to generate a driving signal having afrequency synchronized with a characteristic frequency of the flowsignal of the heat-absorbing medium in accordance with thecharacteristic frequency of the flow signal and a characteristic of theheat dissipating opening, and including an amplifier to amplify thedriving signal; and a vibrator, in response to the driving signal, toapply acoustic waves to the heat-absorbing medium within the housing,wherein the heat-generating component, the acoustic vibrator, and theheat dissipating opening are spaced-apart from each other by apredetermined distance to maximize the heat transfer.
 12. The acousticconvection apparatus of claim 11, wherein the driver comprises: ananalyzer that analyzes the flow signal detected and determines acharacteristic of the flow signal detected by the signal detector; asynchronizer that provides a signal representing a characteristicdetermined in the analyzer; a signal generator that generates the drivesignal in response to the signal provided from the synchronizer; and theamplifier that amplifies the drive signal to a predetermined level. 13.A temperature control apparatus to enhance a convection flow of aheat-absorbing medium in a housing thereof, the temperature controlapparatus comprising: a heat-generating component; a heat dissipatingopening provided through a wall of the housing; a signal detector toreceive a flow signal of a heat-absorbing medium of the housing; adriver to generate a frequency signal synchronized with a characteristicfrequency of the heat-absorbing medium, to generate a driving signalwith a predetermined frequency corresponding to the generated frequencysignal and a characteristic of the heat dissipating opening, andincluding an amplifier to amplify the driving signal; and an acousticvibrator that provides acoustic waves to the heat-absorbing medium inresponse to the amplified driving signal of the driver, the acousticwaves activating heat transfer from the heat-generating component to theheat-absorbing medium and to ambient atmosphere through the heatdissipating opening.
 14. The temperature control apparatus of claim 13,wherein the predetermined signal represents at least one of velocity,temperature, pressure and density of a medium disposed in the case. 15.The temperature control apparatus of claim 13, wherein the drivercomprises: a frequency synchronizer that provides the frequency signalrepresenting a characteristic frequency according to the predeterminedsignal; a signal generator that generates the drive signal in responseto the frequency signal; and the amplifier that amplifies the drivesignal to a predetermined level.
 16. The temperature control apparatusof claim 13, wherein the predetermined signal represents at least one ofa size and a type of the case.
 17. The temperature control apparatus ofclaim 13, wherein the predetermined signal represents a temperaturecorresponding to heat generated by the heat-generating component.
 18. Anacoustic convection apparatus to enhance a convective flow of aheat-absorbing medium in an enclosed space of a housing, the acousticconvection apparatus comprising: an opening provided in a first wall ofthe enclosed space; a signal detector to detect a flow signal of aheat-absorbing medium; a driver to generate a frequency signalsynchronized with a characteristic frequency of the flow signal of theheat-absorbing medium, to generate a driving signal with a predeterminedfrequency in response to the frequency signal, and including anamplifier to amplify the drive signal; and a vibrator to generateacoustic waves to the heat-absorbing medium within the enclosed spaceaccording to the driving signal, the acoustic waves activating heattransfer from the heat-generating component through the heat-absorbingmedium and to ambient atmosphere through the opening, wherein: thehousing encloses the heat-generating component and the heat-absorbingmedium, the characteristic frequency is a dominant frequency amonganalyzed frequency components of the flow signal of the heat-absorbingmedium to substantially encourage heat transfer from the at least oneheat-generating component to the heat-absorbing medium and dissipate thetransferred heat to the ambient atmosphere through the opening, thevibrator is provided between and spaced apart from the heat-generatingcomponent and the opening, and the acoustic waves activate heat transferfrom the heat-generating component to the ambient atmosphere through theopening.
 19. The acoustic convection apparatus of claim 18, wherein thedriver comprises: a synchronizer that provides the frequency signalaccording to the predetermined signal; and a signal generator thatgenerates the drive signal in response to the frequency signal; and theamplifier that amplifies the drive signal to a predetermined level. 20.The acoustic convection apparatus of claim 18, wherein the predeterminedsignal represents at least one of velocity, temperature, pressure anddensity of a medium disposed in the acoustic convection apparatus. 21.The acoustic convection apparatus of claim 18, wherein the predeterminedsignal represents at least one of a size and a type of the case.
 22. Theacoustic convection apparatus of claim 18, wherein the predeterminedsignal represents a temperature corresponding to heat generated by theheat-generating component.
 23. The acoustic convection apparatus ofclaim 18, further comprising: second and third walls to form theenclosed space with the first wall, wherein the heat-generatingcomponent is disposed on the second wall, and the vibrator is disposedon the third wall.
 24. The acoustic convection apparatus of claim 23,wherein the third wall is disposed between the wall and the second wall.25. The acoustic convection apparatus of claim 23, wherein the firstwall comprises a second opening through which heat is transferred to theenclosed space from the heat-generating component.
 26. The acousticconvection apparatus of claim 18, wherein the vibrator generates theacoustic waves toward the heat-absorbing medium disposed between theheat-generating component and the opening to reduce a temperaturedifference of the heat-absorbing medium within the enclosed space. 27.An apparatus to promote the cooling of an electronic device enclosing atleast one heat-generating component, comprising: a signal detector toreceive a flow signal of a cooling medium inside the electronic device;a driver, in response to the flow signal from the signal detector, toprovide a driving signal whose frequently is synchronized with acharacteristic frequency of the flow of the cooling medium, wherein saidcharacteristic frequency is a dominant frequency among analyzedfrequency components of the flow signal of the cooling medium; and avibrator, in response to the driving signal, to generate an acousticwave to an interior of the electronic device, wherein the driverincludes one or more of the following: a frequency analyzer to detectthe characteristic frequency of the flow of the cooling medium based onthe flow signal; a frequency synchronizer to provide a frequency signalwhich represents the detected characteristic frequency; a signalgenerator, in response to the frequency signal from the frequencysynchronizer, to provide the driving signal; and an amplifier to amplifythe driving signal to a predefined level.
 28. The apparatus of claim 27,further comprising: a heat dissipating opening formed to dissipate heatgenerated by the at least one heat-generating component to ambientatmosphere according to the acoustic wave generated by the vibrator. 29.An apparatus to promote the cooling of an electronic device enclosing atleast one heat-generating component, comprising: a signal detector toreceive a flow signal of a cooling medium inside the electronic device;a driver, in response to the flow signal from the signal detector, toprovide a driving signal whose frequently is synchronized with acharacteristic frequency of the flow of the cooling medium, wherein saidcharacteristic frequency is a dominant frequency among analyzedfrequency components of the flow signal of the cooling medium; and avibrator, in response to the driving signal, to generate an acousticwave to an interior of the electronic device, wherein the driverincludes a frequency synchronizer to provide a frequency signal whichrepresents the detected characteristic frequency as the driving signal.30. An apparatus to promote the cooling of an electronic deviceenclosing at least one heat-generating component, comprising: a signaldetector to receive a flow signal of a cooling medium inside theelectronic device; a driver, in response to the flow signal from thesignal detector, to provide a driving signal whose frequently issynchronized with a characteristic frequency of the flow of the coolingmedium, wherein said characteristic frequency is a dominant frequencyamong analyzed frequency components of the flow signal of the coolingmedium; and a vibrator, in response to the driving signal, to generatean acoustic wave to an interior of the electronic device, wherein thedriver includes a signal generator to generate the driving signal inresponse to a frequency signal representing the characteristicfrequency.